A bit premature for that kind of joke, don't you think?
The specific circumstances of the incident will affect what we call it.
If the chamber was extremely hot, and the cartridge discharged due to spontaneously igniting, that's called "cooking off". Generally only seems to happen with extreme rapid fire and/or extremely hot weather.
If a cartridge is chambered and immedately discarges without the trigger being used, that is called a "slam fire" in most cases. It's usually due to the firing pin getting stuck in the forward position and protruding from the bolt face to strike the primer when the action slams shut.
If you pull the trigger and the firing pin hits the primer and nothing happens, then a short time later the cartridge discharges that is called a "hang fire". From what I've heard these are fairly rare nowadays, though I suppose you might run into these if using old reloading components.
In any case if your gun goes click when it should go bang, or goes bang when it should click, it is a serious problem and should be investigated. It could be a sign of an imminent critical malfunction, people have ignored it and had their gun explode afterwards.
If a cartridge is chambered and you discharge, we call that "wacking off".